Reza Ghaffari Sani; Foroogh Dastoorian; seyed Majid Zabihzadeh; Mohammad Tasooji
Abstract
In recent years, plant oils usage as matrix in natural fiber reinforced polymer composites, has been considered because of increasing environmental concern. In the present research work, acrylated epoxidized soybean oil combined with maleic anhydride and styrene as a matrix and wheat straw flour as filler ...
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In recent years, plant oils usage as matrix in natural fiber reinforced polymer composites, has been considered because of increasing environmental concern. In the present research work, acrylated epoxidized soybean oil combined with maleic anhydride and styrene as a matrix and wheat straw flour as filler was used for making a relatively biodegradable composite. In order to find the optimum synthesis time of resin, during reaction of maleic anhydride with acrylated epoxidized soybean oil, three time level of 60, 90 and 120 min, polymer was prepared and cross link density was determined with “solvent swelling” method. The optimum synthesis time of resin was obtained 90 min. Afterwards, maleated acrylated epoxidised soybean oil was mixed with 25% of styrene and 60 mesh wheat straw flour in three weight ratio of 20, 30 and 40% manually. The combination of resin and wheat straw flour was poured in a steel mold and pressing was applied manually. The die was placed in an oven at temperature of 140oC for one hour. Infrared spectroscopy, Thermogravimetric analysis tensile and impact test was conducted to evaluate and analyze the physical and mechanical properties of the resulted composite. Infrared spectroscopy results showed ether bond formation between hydroxyl groups of wheat straw and carbonyl groups of resin. Water absorption test results showed no statistical difference between water absorption values of three loading of wheat straw till 144 hours of immersion, however at 168 hours of immersion, water absorption values were increased with increase of wheat straw loading. There was no statistical difference between thickness swelling values of composites with different wheat straw loading. With increasing wheat straw loading, tensile strength and modulus was increased significantly. Also the impact strength increased as an increase of wheat straw loading.
Physics and Mechanical Wood
Faezeh Farhadi; Seyed Majid Zabihzadeh; foroogh dastoorian
Abstract
Extensive application of heat treated wood in exterior uses with high relative humidity and high temperature circumstances, necessitates the study of mechanical and creep behavior of them at such situations. The general objective of the present study was investigating the effect of test temperature on ...
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Extensive application of heat treated wood in exterior uses with high relative humidity and high temperature circumstances, necessitates the study of mechanical and creep behavior of them at such situations. The general objective of the present study was investigating the effect of test temperature on creep behavior of heat treated velvet maple wood. Heat treatment was conducted on oven dried maple wood samples at three temperature levels of 160, 175 and 190oC. Four-point static flexural test was conducted for determination of the required load level for creep test in three replications at each treatment temperature levels. For conducting creep tests, three levels of test temperature of 21, 40 and 60oC and duration of 65 hours were considered. Results of flexural test showed that heat treatment led to decreasing the rupture modulus compared to the control one; however, the elastic modulus did not change significantly. Results of creep test showed that with increasing test temperature, instantaneous and creep compliance values increased. With increasing treatment temperature, creep compliance was increased as well. Anti-creep efficiency ratio for evaluating the effect of test temperature on creep value at different levels of treatment showed that generally heat treatment led to decreasing the creep strength compared to the control ones. Heat treatment at temperature of 160oC led to in improvement in creep behavior at higher test temperature, in which the reason was attributed to increase of cellulose crystallinity and lignin condensation reaction, in turn led to lower plasticization of wood at higher test temperature.
Management and Economics wood
Foroogh Dastoorian; Faezeh Farhadi; Fahimeh Hoseinzadeh; majid zabihzadeh
Abstract
The present study was done with the aim of investigation of the effect of heat treatment on chemical and physical properties of Iranian beech and Velvet maple. Results of spectroscopy showed that heat treatment led to decrease of hydroxyl groups which became more sensible with increasing temperature ...
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The present study was done with the aim of investigation of the effect of heat treatment on chemical and physical properties of Iranian beech and Velvet maple. Results of spectroscopy showed that heat treatment led to decrease of hydroxyl groups which became more sensible with increasing temperature up to 175oC. Treatment at 190oC led to an increase of hydroxyl group comparing to the control ones. Increasing cellulose crystallinity, decreasing the hemicellulose content, increasing the lignin ratio, degradation of syringyl lignin and increase the condensation reaction of lignin was also obtained from spectroscopy. Results of water absorption tests also showed that heat treatment caused decreasing of water absorption. The water repellent and anti-swelling efficiency for both species showed that heat treatment at 160oC didn’t improve the water repellency and dimensional stability however treatment at 190oC led to decrease of water absorbance specially in beech. In total, the effect of heat treatment on anti-swelling efficiency in beech was more considerable comparing to acer, which can be explained by higher weight loss after heat treatment.
Physics and Mechanical Wood
foroogh dastoorian; Mohammad Layeghi; Ghanbar Ebrahimi; Mehdi Tajvidi; Seid Majid Zabihzadeh
Abstract
In the present study, creep rupture behavior of a bagasse fiber- polypropylene composite was investigated. Two accumulated damage model (EDRM and Wood) and an energy based failure model (R-W) were adopted to describe the load duration influence on the studied composite. Results have shown that at very ...
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In the present study, creep rupture behavior of a bagasse fiber- polypropylene composite was investigated. Two accumulated damage model (EDRM and Wood) and an energy based failure model (R-W) were adopted to describe the load duration influence on the studied composite. Results have shown that at very high stress levels, the EDRM and Wood models underestimated and overestimated the time to failure than static value respectively. This was attributed to the difference between application of static loading and creep loading. Findings indicated that the all three models were able to describe the creep rupture behavior of the studied composite and among this; the Wood model has shown a better fitting with experimental data, statistically. Based on findings in the present research, it can be concluded that the R-W model was more conservative in predicting time to failure in comparison with the two other models, and the reason can be attributed to the difference between failure criteria in energy based models and accumulated damage models. Results also showed that with increasing stress levels, the secondary stage of creep will shorten and at high stress level, the tertiary stage of creep will be more dominant
